A heat dissipation device includes a heat sink (20), heat pipes (30), a frame (40), and a fan (50). Each heat pipe has a lower first connecting portion (32) and an upper second connecting portion (34). The heat sink includes a base (21), and parallel fins (27) attached on the base. The base includes a top plate (25), and defines a hermetically sealed chamber. Apertures (23) are defined in one side wall (22) of the base, the apertures receiving the first connecting portions. Through holes (29) are transversely defined through the fins, the through holes receiving the second connecting portions. The frame includes an upper plate (41), and two side plates (47). Two arms (49) of each side plate secures the frame on the heat sink. In operation, working liquid in the chamber transfers heat to the top plate and to the second connecting portions by phase transition.